drivers/pwm/pwm-renesas-tpu.c

   1 /*
   2  * R-Mobile TPU PWM driver
   3  *
   4  * Copyright (C) 2012 Renesas Solutions Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #include <linux/clk.h>
  17 #include <linux/err.h>
  18 #include <linux/io.h>
  19 #include <linux/init.h>
  20 #include <linux/ioport.h>
  21 #include <linux/module.h>
  22 #include <linux/mutex.h>
  23 #include <linux/platform_data/pwm-renesas-tpu.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/pm_runtime.h>
  26 #include <linux/pwm.h>
  27 #include <linux/slab.h>
  28 #include <linux/spinlock.h>
  29
  30 #define TPU_TSTR                0x00    /* Timer start register (shared) */
  31
  32 #define TPU_TCRn                0x00    /* Timer control register */
  33 #define TPU_TCR_CCLR_NONE       (0 << 5)
  34 #define TPU_TCR_CCLR_TGRA       (1 << 5)
  35 #define TPU_TCR_CCLR_TGRB       (2 << 5)
  36 #define TPU_TCR_CCLR_TGRC       (5 << 5)
  37 #define TPU_TCR_CCLR_TGRD       (6 << 5)
  38 #define TPU_TCR_CKEG_RISING     (0 << 3)
  39 #define TPU_TCR_CKEG_FALLING    (1 << 3)
  40 #define TPU_TCR_CKEG_BOTH       (2 << 3)
  41 #define TPU_TMDRn               0x04    /* Timer mode register */
  42 #define TPU_TMDR_BFWT           (1 << 6)
  43 #define TPU_TMDR_BFB            (1 << 5)
  44 #define TPU_TMDR_BFA            (1 << 4)
  45 #define TPU_TMDR_MD_NORMAL      (0 << 0)
  46 #define TPU_TMDR_MD_PWM         (2 << 0)
  47 #define TPU_TIORn               0x08    /* Timer I/O control register */
  48 #define TPU_TIOR_IOA_0          (0 << 0)
  49 #define TPU_TIOR_IOA_0_CLR      (1 << 0)
  50 #define TPU_TIOR_IOA_0_SET      (2 << 0)
  51 #define TPU_TIOR_IOA_0_TOGGLE   (3 << 0)
  52 #define TPU_TIOR_IOA_1          (4 << 0)
  53 #define TPU_TIOR_IOA_1_CLR      (5 << 0)
  54 #define TPU_TIOR_IOA_1_SET      (6 << 0)
  55 #define TPU_TIOR_IOA_1_TOGGLE   (7 << 0)
  56 #define TPU_TIERn               0x0c    /* Timer interrupt enable register */
  57 #define TPU_TSRn                0x10    /* Timer status register */
  58 #define TPU_TCNTn               0x14    /* Timer counter */
  59 #define TPU_TGRAn               0x18    /* Timer general register A */
  60 #define TPU_TGRBn               0x1c    /* Timer general register B */
  61 #define TPU_TGRCn               0x20    /* Timer general register C */
  62 #define TPU_TGRDn               0x24    /* Timer general register D */
  63
  64 #define TPU_CHANNEL_OFFSET      0x10
  65 #define TPU_CHANNEL_SIZE        0x40
  66
  67 enum tpu_pin_state {
  68         TPU_PIN_INACTIVE,               /* Pin is driven inactive */
  69         TPU_PIN_PWM,                    /* Pin is driven by PWM */
  70         TPU_PIN_ACTIVE,                 /* Pin is driven active */
  71 };
  72
  73 struct tpu_device;
  74
  75 struct tpu_pwm_device {
  76         bool timer_on;                  /* Whether the timer is running */
  77
  78         struct tpu_device *tpu;
  79         unsigned int channel;           /* Channel number in the TPU */
  80
  81         enum pwm_polarity polarity;
  82         unsigned int prescaler;
  83         u16 period;
  84         u16 duty;
  85 };
  86
  87 struct tpu_device {
  88         struct platform_device *pdev;
  89         struct tpu_pwm_platform_data *pdata;
  90         struct pwm_chip chip;
  91         spinlock_t lock;
  92
  93         void __iomem *base;
  94         struct clk *clk;
  95 };
  96
  97 #define to_tpu_device(c)        container_of(c, struct tpu_device, chip)
  98
  99 static void tpu_pwm_write(struct tpu_pwm_device *pwm, int reg_nr, u16 value)
 100 {
 101         void __iomem *base = pwm->tpu->base + TPU_CHANNEL_OFFSET
 102                            + pwm->channel * TPU_CHANNEL_SIZE;
 103
 104         iowrite16(value, base + reg_nr);
 105 }
 106
 107 static void tpu_pwm_set_pin(struct tpu_pwm_device *pwm,
 108                             enum tpu_pin_state state)
 109 {
 110         static const char * const states[] = { "inactive", "PWM", "active" };
 111
 112         dev_dbg(&pwm->tpu->pdev->dev, "%u: configuring pin as %s\n",
 113                 pwm->channel, states[state]);
 114
 115         switch (state) {
 116         case TPU_PIN_INACTIVE:
 117                 tpu_pwm_write(pwm, TPU_TIORn,
 118                               pwm->polarity == PWM_POLARITY_INVERSED ?
 119                               TPU_TIOR_IOA_1 : TPU_TIOR_IOA_0);
 120                 break;
 121         case TPU_PIN_PWM:
 122                 tpu_pwm_write(pwm, TPU_TIORn,
 123                               pwm->polarity == PWM_POLARITY_INVERSED ?
 124                               TPU_TIOR_IOA_0_SET : TPU_TIOR_IOA_1_CLR);
 125                 break;
 126         case TPU_PIN_ACTIVE:
 127                 tpu_pwm_write(pwm, TPU_TIORn,
 128                               pwm->polarity == PWM_POLARITY_INVERSED ?
 129                               TPU_TIOR_IOA_0 : TPU_TIOR_IOA_1);
 130                 break;
 131         }
 132 }
 133
 134 static void tpu_pwm_start_stop(struct tpu_pwm_device *pwm, int start)
 135 {
 136         unsigned long flags;
 137         u16 value;
 138
 139         spin_lock_irqsave(&pwm->tpu->lock, flags);
 140         value = ioread16(pwm->tpu->base + TPU_TSTR);
 141
 142         if (start)
 143                 value |= 1 << pwm->channel;
 144         else
 145                 value &= ~(1 << pwm->channel);
 146
 147         iowrite16(value, pwm->tpu->base + TPU_TSTR);
 148         spin_unlock_irqrestore(&pwm->tpu->lock, flags);
 149 }
 150
 151 static int tpu_pwm_timer_start(struct tpu_pwm_device *pwm)
 152 {
 153         int ret;
 154
 155         if (!pwm->timer_on) {
 156                 /* Wake up device and enable clock. */
 157                 pm_runtime_get_sync(&pwm->tpu->pdev->dev);
 158                 ret = clk_prepare_enable(pwm->tpu->clk);
 159                 if (ret) {
 160                         dev_err(&pwm->tpu->pdev->dev, "cannot enable clock\n");
 161                         return ret;
 162                 }
 163                 pwm->timer_on = true;
 164         }
 165
 166         /*
 167          * Make sure the channel is stopped, as we need to reconfigure it
 168          * completely. First drive the pin to the inactive state to avoid
 169          * glitches.
 170          */
 171         tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
 172         tpu_pwm_start_stop(pwm, false);
 173
 174         /*
 175          * - Clear TCNT on TGRB match
 176          * - Count on rising edge
 177          * - Set prescaler
 178          * - Output 0 until TGRA, output 1 until TGRB (active low polarity)
 179          * - Output 1 until TGRA, output 0 until TGRB (active high polarity
 180          * - PWM mode
 181          */
 182         tpu_pwm_write(pwm, TPU_TCRn, TPU_TCR_CCLR_TGRB | TPU_TCR_CKEG_RISING |
 183                       pwm->prescaler);
 184         tpu_pwm_write(pwm, TPU_TMDRn, TPU_TMDR_MD_PWM);
 185         tpu_pwm_set_pin(pwm, TPU_PIN_PWM);
 186         tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
 187         tpu_pwm_write(pwm, TPU_TGRBn, pwm->period);
 188
 189         dev_dbg(&pwm->tpu->pdev->dev, "%u: TGRA 0x%04x TGRB 0x%04x\n",
 190                 pwm->channel, pwm->duty, pwm->period);
 191
 192         /* Start the channel. */
 193         tpu_pwm_start_stop(pwm, true);
 194
 195         return 0;
 196 }
 197
 198 static void tpu_pwm_timer_stop(struct tpu_pwm_device *pwm)
 199 {
 200         if (!pwm->timer_on)
 201                 return;
 202
 203         /* Disable channel. */
 204         tpu_pwm_start_stop(pwm, false);
 205
 206         /* Stop clock and mark device as idle. */
 207         clk_disable_unprepare(pwm->tpu->clk);
 208         pm_runtime_put(&pwm->tpu->pdev->dev);
 209
 210         pwm->timer_on = false;
 211 }
 212
 213 /* -----------------------------------------------------------------------------
 214  * PWM API
 215  */
 216
 217 static int tpu_pwm_request(struct pwm_chip *chip, struct pwm_device *_pwm)
 218 {
 219         struct tpu_device *tpu = to_tpu_device(chip);
 220         struct tpu_pwm_device *pwm;
 221
 222         if (_pwm->hwpwm >= TPU_CHANNEL_MAX)
 223                 return -EINVAL;
 224
 225         pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
 226         if (pwm == NULL)
 227                 return -ENOMEM;
 228
 229         pwm->tpu = tpu;
 230         pwm->channel = _pwm->hwpwm;
 231         pwm->polarity = tpu->pdata ? tpu->pdata->channels[pwm->channel].polarity
 232                       : PWM_POLARITY_NORMAL;
 233         pwm->prescaler = 0;
 234         pwm->period = 0;
 235         pwm->duty = 0;
 236
 237         pwm->timer_on = false;
 238
 239         pwm_set_chip_data(_pwm, pwm);
 240
 241         return 0;
 242 }
 243
 244 static void tpu_pwm_free(struct pwm_chip *chip, struct pwm_device *_pwm)
 245 {
 246         struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
 247
 248         tpu_pwm_timer_stop(pwm);
 249         kfree(pwm);
 250 }
 251
 252 static int tpu_pwm_config(struct pwm_chip *chip, struct pwm_device *_pwm,
 253                           int duty_ns, int period_ns)
 254 {
 255         static const unsigned int prescalers[] = { 1, 4, 16, 64 };
 256         struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
 257         struct tpu_device *tpu = to_tpu_device(chip);
 258         unsigned int prescaler;
 259         bool duty_only = false;
 260         u32 clk_rate;
 261         u32 period;
 262         u32 duty;
 263         int ret;
 264
 265         /*
 266          * Pick a prescaler to avoid overflowing the counter.
 267          * TODO: Pick the highest acceptable prescaler.
 268          */
 269         clk_rate = clk_get_rate(tpu->clk);
 270
 271         for (prescaler = 0; prescaler < ARRAY_SIZE(prescalers); ++prescaler) {
 272                 period = clk_rate / prescalers[prescaler]
 273                        / (NSEC_PER_SEC / period_ns);
 274                 if (period <= 0xffff)
 275                         break;
 276         }
 277
 278         if (prescaler == ARRAY_SIZE(prescalers) || period == 0) {
 279                 dev_err(&tpu->pdev->dev, "clock rate mismatch\n");
 280                 return -ENOTSUPP;
 281         }
 282
 283         if (duty_ns) {
 284                 duty = clk_rate / prescalers[prescaler]
 285                      / (NSEC_PER_SEC / duty_ns);
 286                 if (duty > period)
 287                         return -EINVAL;
 288         } else {
 289                 duty = 0;
 290         }
 291
 292         dev_dbg(&tpu->pdev->dev,
 293                 "rate %u, prescaler %u, period %u, duty %u\n",
 294                 clk_rate, prescalers[prescaler], period, duty);
 295
 296         if (pwm->prescaler == prescaler && pwm->period == period)
 297                 duty_only = true;
 298
 299         pwm->prescaler = prescaler;
 300         pwm->period = period;
 301         pwm->duty = duty;
 302
 303         /* If the channel is disabled we're done. */
 304         if (!test_bit(PWMF_ENABLED, &_pwm->flags))
 305                 return 0;
 306
 307         if (duty_only && pwm->timer_on) {
 308                 /*
 309                  * If only the duty cycle changed and the timer is already
 310                  * running, there's no need to reconfigure it completely, Just
 311                  * modify the duty cycle.
 312                  */
 313                 tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
 314                 dev_dbg(&tpu->pdev->dev, "%u: TGRA 0x%04x\n", pwm->channel,
 315                         pwm->duty);
 316         } else {
 317                 /* Otherwise perform a full reconfiguration. */
 318                 ret = tpu_pwm_timer_start(pwm);
 319                 if (ret < 0)
 320                         return ret;
 321         }
 322
 323         if (duty == 0 || duty == period) {
 324                 /*
 325                  * To avoid running the timer when not strictly required, handle
 326                  * 0% and 100% duty cycles as fixed levels and stop the timer.
 327                  */
 328                 tpu_pwm_set_pin(pwm, duty ? TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
 329                 tpu_pwm_timer_stop(pwm);
 330         }
 331
 332         return 0;
 333 }
 334
 335 static int tpu_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *_pwm,
 336                                 enum pwm_polarity polarity)
 337 {
 338         struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
 339
 340         pwm->polarity = polarity;
 341
 342         return 0;
 343 }
 344
 345 static int tpu_pwm_enable(struct pwm_chip *chip, struct pwm_device *_pwm)
 346 {
 347         struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
 348         int ret;
 349
 350         ret = tpu_pwm_timer_start(pwm);
 351         if (ret < 0)
 352                 return ret;
 353
 354         /*
 355          * To avoid running the timer when not strictly required, handle 0% and
 356          * 100% duty cycles as fixed levels and stop the timer.
 357          */
 358         if (pwm->duty == 0 || pwm->duty == pwm->period) {
 359                 tpu_pwm_set_pin(pwm, pwm->duty ?
 360                                 TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
 361                 tpu_pwm_timer_stop(pwm);
 362         }
 363
 364         return 0;
 365 }
 366
 367 static void tpu_pwm_disable(struct pwm_chip *chip, struct pwm_device *_pwm)
 368 {
 369         struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
 370
 371         /* The timer must be running to modify the pin output configuration. */
 372         tpu_pwm_timer_start(pwm);
 373         tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
 374         tpu_pwm_timer_stop(pwm);
 375 }
 376
 377 static const struct pwm_ops tpu_pwm_ops = {
 378         .request = tpu_pwm_request,
 379         .free = tpu_pwm_free,
 380         .config = tpu_pwm_config,
 381         .set_polarity = tpu_pwm_set_polarity,
 382         .enable = tpu_pwm_enable,
 383         .disable = tpu_pwm_disable,
 384         .owner = THIS_MODULE,
 385 };
 386
 387 /* -----------------------------------------------------------------------------
 388  * Probe and remove
 389  */
 390
 391 static int tpu_probe(struct platform_device *pdev)
 392 {
 393         struct tpu_device *tpu;
 394         struct resource *res;
 395         int ret;
 396
 397         tpu = devm_kzalloc(&pdev->dev, sizeof(*tpu), GFP_KERNEL);
 398         if (tpu == NULL) {
 399                 dev_err(&pdev->dev, "failed to allocate driver data\n");
 400                 return -ENOMEM;
 401         }
 402
 403         tpu->pdata = pdev->dev.platform_data;
 404
 405         /* Map memory, get clock and pin control. */
 406         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 407         if (!res) {
 408                 dev_err(&pdev->dev, "failed to get I/O memory\n");
 409                 return -ENXIO;
 410         }
 411
 412         tpu->base = devm_ioremap_resource(&pdev->dev, res);
 413         if (IS_ERR(tpu->base))
 414                 return PTR_ERR(tpu->base);
 415
 416         tpu->clk = devm_clk_get(&pdev->dev, NULL);
 417         if (IS_ERR(tpu->clk)) {
 418                 dev_err(&pdev->dev, "cannot get clock\n");
 419                 return PTR_ERR(tpu->clk);
 420         }
 421
 422         /* Initialize and register the device. */
 423         platform_set_drvdata(pdev, tpu);
 424
 425         spin_lock_init(&tpu->lock);
 426         tpu->pdev = pdev;
 427
 428         tpu->chip.dev = &pdev->dev;
 429         tpu->chip.ops = &tpu_pwm_ops;
 430         tpu->chip.base = -1;
 431         tpu->chip.npwm = TPU_CHANNEL_MAX;
 432
 433         ret = pwmchip_add(&tpu->chip);
 434         if (ret < 0) {
 435                 dev_err(&pdev->dev, "failed to register PWM chip\n");
 436                 return ret;
 437         }
 438
 439         dev_info(&pdev->dev, "TPU PWM %d registered\n", tpu->pdev->id);
 440
 441         pm_runtime_enable(&pdev->dev);
 442
 443         return 0;
 444 }
 445
 446 static int tpu_remove(struct platform_device *pdev)
 447 {
 448         struct tpu_device *tpu = platform_get_drvdata(pdev);
 449         int ret;
 450
 451         ret = pwmchip_remove(&tpu->chip);
 452         if (ret)
 453                 return ret;
 454
 455         pm_runtime_disable(&pdev->dev);
 456
 457         return 0;
 458 }
 459
 460 static struct platform_driver tpu_driver = {
 461         .probe          = tpu_probe,
 462         .remove         = tpu_remove,
 463         .driver         = {
 464                 .name   = "renesas-tpu-pwm",
 465                 .owner  = THIS_MODULE,
 466         }
 467 };
 468
 469 module_platform_driver(tpu_driver);
 470
 471 MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
 472 MODULE_DESCRIPTION("Renesas TPU PWM Driver");
 473 MODULE_LICENSE("GPL v2");
 474 MODULE_ALIAS("platform:renesas-tpu-pwm");